Centrifugal powdering machine

ABSTRACT

A powdering machine utilizing centrifugal force in which there is provided a jacket having percussion protrusions all over the surface of its barrel inner wall, a perforated cylindrical stationary screen inserted removably and fitted in the jacket and a perforated cylindrical rotary screen and beating bars both installed rotatably in the stationary screen so that if the objects to be powdered are deposited in the rotary screen they may be first beaten by the beating bars and then thrown against the percussion protrusions through the holes of the stationary screen by the centrifugal force of the rotary screen and pulverized into powder.

United States Patent [72] Inventors Kazuteru Tako References Cited 19131-203, Z-chome, llasune, ltabashi-ku, UNITED STATES PATENTS yo; mroshi Gun, 1327, om Yours 1,212,273 21c? 241/90 X smma both ouapm n erson.... 24l I85 [211 pp No 227 1,991,899 2/1935 l-lolbeck 241/163 X [22] Filed Jan. 2, 1970 Primary Examiner-Andrew R. Juhasz Patented Dec. 21, 1971 Assistant Examiner-Gary L. Smith [32] Priority Jan. 22, 1969 Attorney-Holman & Stern [33] Japan [3i] 44/4588 ABSTRACT: A powdering machine utilizing centrifugal force in which there is provided a jacket having percussion protru- [54] CENTRIFUGAL POWDERING MACIIlNE sions all over the surface of its barrel inner wall, a erforated P 1 Claim, 2 Drawing Figs. cylindrical stationary screen inserted removably and fitted in the jacket and a perforated cylindrical rotary screen and beat- [52] U.S.Cl 241/2153] g has both instaned mmtably in the stationary screen so [51] In Cl 802C 17/02 that if the objects to be powdered are deposited in the rotary 02c 13/282, screen y y be first beaten y the beating bars and then Field 0 S arch 241 thrown against the percussion protrusions through the holes of 77 6 146/300 the stationary screen by the centrifugal force of the rotary 341/275 screen and pulverized into powder.

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. II n 27 i O G O 28- mmrz'a: II 3 0 7 11 PATENTED 08:21 87! CENTRIFUGAL POWDERING MACHINE BACKGROUND OF THE INVENTION Existing methods adopted in powdering machines of this kind include the method of cutting and crushing the objects to be powdered charged in a powdering chamber by means of rotary cutting tools, the method of pulverizing the objects in a powdering chamber having fixed percussion teeth or barshaped protrusions and a rotary disc engaging with teeth or protrusions, the method of beating the objects in a powdering chamber having a rotating disc provided with hammers and the method of powdering the objects by sucking them together with a stream of air from one into another of several rotating powdering chambers. All these existing methods, however, have proved to be unsatisfactory for producing fine particles having grain diameters in specified ranges and at high rates of yield, although they can produce particles having some nonuniform grain diameters.

In addition, the operation by these methods is of ten confronted with troubles in the pulverization of synthetic resins in particular, for if the powdering of thermoplastic resins is continued for long periods of time by these methods they will tend to soften and finallyfuse by the heat generated by internal friction, while if the powdering of thermosetting resins is continued they will tend to harden by such heat and make the smooth operation difiicult.

The centrifugal powdering machine of the present invention is a marked improvement on the existing machines adopting such imperfect methods. It not only eliminates the above-mentioned disadvantages and troubles but also simplifies the construction and enhances the productivity.

SUMMARY OF THE INVENTION The present invention relates to a centrifugal powdering machine which comprises a jacket having percussion protrusions all over the surface of the inner wall of its cylindrical barrel, the inside of the jacket serving as a powdering chamber, a disc mounted on the rotary shaft provided at the center of the projecting shell portion of the powdering chamber, a perforated cylindrical rotary screen and beating bars both fitted rotatably to the disc, a perforated cylindrical stationary screen inserted removably between the inner wall of the barrel and the perforated cylindrical rotary screen, an inlet pipe portion fitted to the cover of the barrel for connecting a hopper and feeder at the powdering chamber and a discharge port provided at the bottom of the powdering chamber.

It is the main object of the present invention to break up hard materials like plastics and glass or granular materials like pigments into fine powder having a uniform particle size by laying them in the powdering chamber and pulverizing them by the beating bars and rotary screen.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section of the entire part of the powdering machine, shown with a part of its rotary screen cut off.

FIG. 2 is a section taken along line II II of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT One side of a cylindrical barrel 1 of the jacket is provided with a portion 2 forming the bottom, and the other open side is closed by a cover 3. The interior of inner wall 5 of the barrel l is a void 7 for passing liquid 29, with the void 7 being provided with an inlet 8 and an outlet 9 so that the liquid 29 can circulate to cool the barrel 1 and its interior. The inner wall 5 of the barrel 1 is provided all over its inside surface with percussion protrusions 6, with the hollow space further inside forming a powdering chamber 20. In the hollow space defined by the inner wall 5 of the barrel 1 is provided a cylindrical stationary sleeve or screen 10 having numerous holes It and fitted removably to a sideplate 4 which forms the bottom of the barrel l. The stationary screen 10 may be fitted to the sideplate 4 by providing an annular groove 30 or annular protrusion for the sideplate 4. Since this stationary screen 10 is supported also by the cover 3 it is fixed securely. Inside this stationary screen 10 is provided a cylindrical rotary sleeve or screen 12, which has numerous holes 13. This rotary screen I2 is mounted removably on a disc 14 which is mounted removably on a rotary shaft so that both the rotary screen 12 and the disc M can rotate together. To the disc 14 are fixed several beating bars 16 in parallel with the rotary screen 12, and they serve to crush and agitate objects 28 to be powdered in the rotary screen 12. Through the center of a boss 17 of the portion 2 of the barrel I is inserted the rotary shaft 15 which can be rotated at a high speed by driving pulley 27. The cover 3 mounted on the other side of the barrel 1 is provided at its center with an inlet pipe portion which communicates with the powdering chamber 20. To this pipe portion 21 is connected a conduit 23 which leads to a hopper 22. The conduit 23 contains a screw 24 or a suitable feeder which is mounted on a rotary shaft 25. At a suitable position of the lower portion of the barrell is a discharge port 26 for the powdering chamber 20 opening from the inner wall 5 to the exterior of the barrel.

The objects 28 to be powdered charged into the hopper 22 are deposited in the powdering chamber 20 by the feeder. As the driving pulley 27 is rotated by power supplied from a power source, the disc 14 rotates at a high speed on the rotary shaft 15 to set the rotary screen 12 and the beating bars 16 into rotation at the same time. The objects 28 carried into the interior of this rotary screen 12 strike against the rotating disc 14, are beaten and crushed roughly by the beating bars 16, discharged from the rotary screen 12 through the holes 13 by the centrifugal force of the rotary screen 12 and dashed violently against the stationary screen 10 provided at the outside of the rotary screen 12 to be further pulverized into fine powder. In this case, the objects 28 are crushed extremely finely in the void between the internal rotary screen 2 and the external stationary screen 10 because the screen 12 is rotating at a high speed and the screen 10 is placed close to the screen 12. Both the rotary screen 12 and stationary screen 10, mounted removably on the disc 14 and on the bottom plate 4 respectively, are replaceable. Therefore, an excellent powdering condition can be obtained and the grains roughly crushed by the round or square beating bars 16 fixed to the disc 14 can be pulverized very finely by proper selection and combination of screens 10 and 12 having ideal sizes of holes 11 and 13 depending on the objects to be powdered 28. The fine particles thus obtained are blown out through the holes 11 of the stationary screen 10 by the wind pressure caused by the rotary screen 12 and dashed against the percussion protrusions 6 provided on the inner wall 5 which define the powdering chamber 20 and further pulverized into fine powder. The powder thus obtained is removed through the discharge port 26.

This machine, s described above, depends mainly on the beating bars 16, the rotary screen 12, the stationary screen 10 and the percussion protrusions 6 for the powdering operation. Thus its rotary shaft 15, disc 14, beating bars 16, etc. are heated by the frictional heat during the operation, with the result that the objects 28, especially in the case of thermoplastic synthetic resins, tend to soften. As such softened materials stick to each part of the powdering chamber 20 to cause troubles in the operation, liquid (water) 29 is always kept circulating in the void 7 of the inner wall 5 of the barrel 1 to cool the rotary shaft R5, the disc 14, the beating bars 16, etc., as well as the interior of the powdering chamber and the percussion protrusions 6. Hence, the heat troubles are avoided and the objects 28 are prevented from quality changes. Furthermore, the operation can be carried out very smoothly and powder having any desired particle size can be obtained at high efficiency. Thus it is possible to pulverize all kinds of plastic materials like thermoplastic and thermosetting synthetic resins, hard materials like glass and granular materials like pigments and paints into fine powder thereby largely improving various industrial effects.

We claim:

l. A centrifugal powdering machine for materials, particularly synthetic resins, comprising a cylindrical barrel having an open end and a closed end, a cover for the open end, said barrel having sidewalls and an end wall spaced inwardly of the barrel for providing a space through which a cooling medium may circulate, said sidewall having an inner surface provided with percussion protrusions entirely thereabout, with the space defined by the sidewalls and end wall constituting a powdering chamber closed by said cover, a disc within the chamber adjacent the end wall, means mounting the disc for rotation relative to the end wall, with said disc being removable from the powdering chamber, said disc having a plurality of beating bars extending axially of the chamber and terminating adjacent said cover, a first perforated cylindrical sleeve removably supported by the disc and surrounding the beater bars, a second perforated cylindrical sleeve having an inner diameter slightly greater than the outer diameter of the first cylindrical sleeve surrounding the first cylindrical sleeve, said second cylindrical sleeve being stationarily supported by the end wall and the cover and being removable from said end wall and cover, means for introducing the material to be powdered through the cover into the powdering chamber, and a discharge means leading from the chamber to the exterior of the barrel, the arrangement being such that upon rotation of the disc, the first sleeve and bars rotate therewith relative to the second cylindrical sleeve with the bars crushing and agitating the material which is discharged from the first sleeve via centrifugal action through the perforations therein through the perforations in the second sleeve into the second sleeve, with the perforations of the first and second sleeve coacting to effect a shearing action on the material, and the material in the second sleeve being discharged through the perforations thereof, due to the wind pressure developed by the rotation of the first sleeve for additional pulverization by the percussion projections on the inner surface of the sidewall. 

1. A centrifugal powdering machine for materials, particularly synthetic resins, comprising a cylindrical barrel having an open end and a closed end, a cover for the open end, said barrel having sidewalls and an end wall spaced inwardly of the barrel for providing a space through which a cooling medium may circulate, said sidewall having an inner surface provided with percussion protrusions entirely thereabout, with the space defined by the sidewalls and end wall constituting a powdering chamber closed by said cover, a disc within the chamber adjacent the end wall, means mounting the disc for rotation relative to the end wall, with said disc being removable from the powdering chamber, said disc having a plurality of beating bars extending axially of the chamber and terminating adjacent said cover, a first perforated cylindrical sleeve removably supported by the disc and surrounding the beater bars, a second perforated cylindrical sleeve having an inner diameter slightly greater than the outer diameter of the first cylindrical sleeve surrounding the first cylindrical sleeve, said second cylindrical sleeve being stationarily supported by the end wall and the cover and being removable from said end wall and cover, means for introducing the material to be powdered through the cover into the powdering chamber, and a discharge means leading from the chamber to the exterior of the barrel, the arrangement being such that upon rotation of the disc, the first sleeve and bars rotate therewith relative to the second cylindrical sleeve with the bars crushing and agitating the material which is discharged from the first sleeve via centrifugal action through the perforations therein through the perforations in the second sleeve into the second sleeve, with the perforations of the first and second sleeve coacting to effect a shearing action on the material, and the material in the second sleeve being discharged through the perforations thereof, due to the wind pressure developed by the rotation of the first sleeve for additional pulverization by the percussion projections on the inner surface of the sidewall. 